Liquid laundry builder containing alkali hydroxide and borax

ABSTRACT

In an liquid laundry detergent system for the washing of fabrics, clothes and the like, particularly those of the washand-wear type, wherein an aqueous solution of alkali metal hydroxide is employed as the alkaline builder, the improvement of adding to the alkaline builder solution borax in an amount of from about 5 to 15 weight percent of the amount of said hydroxide initially present, so as to form in situ alkali metal metaborate, e.g., sodium metaborate when the builder is sodium hydroxide, so that the available hydroxyl ion concentration of said alkaline builder solution is decreased but its alkalinity and detergency are increased.

United States Patent 1 Ciko et al.

[ LIQUID LAUNDRY BUILDER CONTAINING ALKALI HYDROXIDE AND BORAX [75]Inventors: John D. Ciko, Allen Park; John J.

Cramer, Wyandotte, both of Mich.

[731 Assignee: BASF Wyandotte Corporation,

Wyandotte, Mich.

221 Filed: Nov. 12,1913

21 Appl. No.: 415,238

[52] US. Cl. 8/137; 252/]35; 252/156 [51] Int. CIA... CIID 9/16; Cl 1D7/06; CI [B 7/10 [58] Field of Search 252/99, 103, I09, I35,

[56] References Cited UNITED STATES PATENTS 2,760,927 8/l956 Webster n252/[56 X 2,79l,562 5/l957 Difi'ley 2,932,584 4/ l 960 Hubbell 3,039,9706/l962 Krueger 252/[35 OTHER PUBLICATIONS F. L. Wells et al.:Manufacture of Dissolving Pulps by 1 Dec. 23, 1975 Extraction in SodiumHydroxide-Borax Solutions" Tappi, Vol. 54, No. 4, Apr. 1971, pp.525-529.

Primary ExaminerDennis E. Talbert, Jr.

Assistant Examiner--Dennis L. Albrecht Attorney, Agent, or Firm-BernhardR. Swick; Joseph D. Michaeis; Robert E. Dunn [57] ABSTRACT [n an liquidlaundry detergent system for the washing of fabrics, clothes and thelike, particularly those of the wash-and-wear type, wherein an aqueoussolution of alkali metal hydroxide is employed as the alkaline builder,the improvement of adding to the alkaline builder solution borax in anamount of from about 5 to 15 weight percent of the amount of saidhydroxide initially present, so as to form in situ alkali metalmetaborate, e.g., sodium metaborate when the builder is sodiumhydroxide, so that the available hydroxyl ion concentration of saidalkaline builder solution is decreased but its alkalinity and detergencyare increased.

9 Claims, No Drawings LIQUID LAUNDRY BUILDER CONTAINING ALKALI HYDROXIDEAND BORAX BACKGROUND 1. Field of the Invention This invention relates toan improved liquid alkaline builder for liquid laundry detergentsystems. The new builder is particularly useful for wash-andwear type offabrics containing high amounts of polyester fibers.

2. Description of the Prior Art The increasing use of industrial washingmachines equipped with automatic liquid supply injection systemsconstitutes an important change in the laundry and chemical supplyindustries. No longer will it be possible to use solid products, butrather stock solutions of the detergent, builder, bleach, sour and thelike will be required to keep the supply systems operational. Buildersare included in laundry formulations to enhance the cleaning capacity ofthe detergent being used. For example, alkaline builders extenddetergent capacity by solubilizing soils, hydrolyzing fats, promotingfoam formation and the like. One of the most effective, and onceextensively used, laundry builders is sodium hydroxide, commonly calledcaustic soda. In addition, caustic soda is also economical, very solublein water and germicidally effective. Therefore, people have attemptedfor many years to utilize this builder despite its caustic nature which,in some respects, is a major drawback. Among the alkali metal saltswhich have been used as builders, either as complete or partialreplacement for the alkali matal hydroxides, have been the borates,phosphates, silicates, carbonates and the like.

The detergent art is replete with many instances of attempts to usethese various alkali metal salts in the various branches of detergency.For instance, U.S. Pat. No. 1,869,057 discloses a shaving aid to removeoil film from hair by the use of a dilute aqueous solution of a saltcomposed of a strong base and a weak acid, e.g., a dilute aqueoussolution of potassium or sodium carbonate or borate, either singularlyor in combination. The disclosed solution contains about /2 to 1 percentof a salt and water because at that concentration the hydrolysis issubstantially complete and continuous. At higher concentrations there isan increasing amount of salt which is not hydrolyzed. Another patent inU.S. Pat. No. 2,397,l93 relating to wood bleaching wherein the bleachingcomposition consists of about I volume of an alkali component consistingsubstantially of one part by weight borax, 2 parts by weight causticsoda, and one part by weight of waterglass plus twenty parts by weightof water. Hydrogen peroxide is then added before being used as thebleach.

A later patent, U.S. Pat. No. 3,142,53 l disclosing an industrialprocess for bleaching of gray cotton knit goods suggests as the secondbath of a three-bath series the use of a bleaching solution containinghydrogen peroxide, sodium hydroxide and borax while keeping the goodsimmersed in the peroxide bleaching solution at a temperature of 170 to190 F. for a period of 280 to 320 minutes. A still later U.S. Pat. No.3,529,999, disclo es a method for cleaning natural and artificial stonesby the use of an aqueous solution consisting of an alkali metalhydroxide, a salt from the same alkali metal with a weak acid comingfrom the group of formic, acetic, propionic, lactic, citric, boric,carbonic, hydrofluoric, sulfurous tetraboric and phosphoric acids, athickening agent and water. In this mixture the alkali metal salt of theweak acid content is from 5 to 60% by weight of total composition andpreferably from 5 to 40%. Another recent U.S. Pat. No. 3,5 30,071discloses the use of borax as a stabilizer for chlorinated trisodiumphosphate which is used in conjunction with up to 30% by weight alkalinedetergency builder in an abrasive scouring cleaner.

S. Bernstein and M. Levine in an article published in Food Technology,Volume 3, pages 375-378, Novcmber, I949, note that the addition ofalkaline salt, such as sodium chloride, sodium carbonate, or sodiumphosphate, to a solution of sodium hydroxide appreciably increases thegermicidal properties of the caustic solution. Furthermore, sodiummetaborate acts in an analogous manner but, in contrast to theforegoing, the addition of borax causes a marked reduction in germicidalefficiency. This is due to interaction of borax with the caustic to formsodium metaborate with a corresponding reduction in the concentration ofthe primary germicidal component, namely, sodium hydroxide.

SUMMARY OF THE INVENTION In accordance with this invention there isprovided a liquid laundry detergent system for the washing of fabrics,clothes and the like, particularly those of the washand-wear typecontaining polyester fibers, wherein an aqueous solution of alkali metalhydroxide is employed as the builder, the improvement comprising addingto said solution borax in an amount of from about 5 to I5 weight percentof the amount of said hydroxide initially present, said borax forming insitu alkali metal metaborate, so that the available hydroxyl ionconcentration of said solution is decreased but its alkalinity anddetergency are increased.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a liquid laundry detergentsystem employing an alkaline builder solution, the preferred alkalinematerial is either sodium hydroxide which is often called caustic sodaor potassium hydroxide which is often called potash. Because of costconsiderations sodium hydroxide solutions are widely used even thoughthere is a technical advantage in the use of the potassium hydroxidesolutions. These solutions on a weight percent of total basis containfrom [0 to 30% alkali metal hydroxide and preferably 18 to 22 weightpercent alkali metal hydroxide with a 20% solution being ideal. In thepast, the presence of relatively high concentration of hydroxyl ion inliquid wash formulas has not constituted any real threat to fabrictensile strength, since the preponderance of garments consisted ofcotton. However, with the advent of garments consisting ofpolyester-cotton blends, i.e., wash-and-wear fabrics, the effects ofcaustic upon modern synthetic fibers became increasingly important. Ithas been shown that the extent of damage caused to polyester structuresis directly proportional to the independent variables of exposure time,temperature and molar hydroxyl ion concentration.

An effective means has now been found for reducing caustic soda orcaustic potash available hydroxyl ion concentration, while increasingits detergency by in situ reacting it with the alkali salt sodium borate(Na B,O commonly called borax. The borax reacts with the caustic liquorto form alkali metal borate, e.g., sodium metaborate when caustic sodais used. A mixed alkali metal borate is obtained in the case wherepotash is the builder. Based on the amount of caustic solids initiallyin the solution, it has been found advantageous to add from about toabout weight percent of borax and preferably from about 8 to 12 weightpercent of borax with l0% by weight being preferred. Eight weightpercent of borax with yield l0.4 weight percent sodium metaborate, l0%borax yields 13 weight percent sodium metaborate while 12 weight percentborax yields l5.7 weight percent sodium metaborate. Although the totalalkali concentration of the system is increased, the net availablehydroxyl ion concentration has been reduced. When 2% by weight of boraxis added to a weight percent aqueous solution of caustic soda (so diumhydroxide liquor), the available hydroxyl ions are reduced byapproximately While the borax did reduce the hydroxyl ion concentrationsand, therefore, it would be expected to proportionately reduce itscleaning efficiency, it has been found that just the opposite effect isachieved, namely, that that alkalinity and detergency of the alkalibuilder solution are increased.

lt was quite surprising to find the cleaning efficiency of a liquidlaundry formulation utilizing an alkaline builder of only caustic sodaand a liquid alkaline builder containing the same amount of caustic sodaplus 20% borax (by weight of the initially present caustic soda) had thesame cleaning efficiency. Whereas lesser amounts of borax added to thealkaline builder in the same liquid cleaning system had increasingamounts of efficiency and this synergistic effect approached the maximumwhen the amount of borax was 10% by weight of the amount of causticinitially in the alkaline builder solution.

In the liquid detergent system it is conventional and desirable to addto the formulation an anti-redeposition agent so as to prevent the soilwhich has been removed from the fabric being redeposited on the fabricduring the subsequent period of washing. However, in a liquid system thetypical surfactant employed is not readily compatible with ananti-redeposition agent and, therefore, must be injected into the washvia a different conduit. It has been found practical and useful to addthe anti-redeposition agent in the alkaline builder solution. Thepresence of the anti-redeposition agent in the alkaline builder solutionof this invention in no way inhibits or materially changes the inventionwhich has been discovered. The amount of anti-redeposition agent addedto the alkaline builder solution can range from about 0.25 weightpercent to about l.5 weight percent with a typical amount being 0.75 to1%. Typical anti-redeposition agents employed include the alkali andammonium salts of carboxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose and the like.

The alkaline builder solution of this invention is added to the wash inthe conventional manner for utilizing liquid detergent systems. Theamount of alkaline builder to be added, of course, will be variedaccording to the total detergency desired in the particular wash. Thesevariations and ratios are well known in the art and the use of thisinvention does not entail any modifications other than those which wouldbe immediately obvious to those of ordinary skill in the art. Therefore,for the sake of brevity further elucidation of the obvious will not bemade at this time.

The practice of this invention is illustrated by, but not limited by,the examples given below. Unless otherwise LII noted, temperature isexpressed in degrees centigrade and parts are parts by weight.

EXAMPLE I A liquid alkaline builder solution was prepared containing 20%by weight caustic soda and by weight of water. The pH of a 0.2% aqueoussolution of this builder was ll.8. The solution when titrated withhydrochloric acid had a typical strong acid-strong based titrationcurve. The amount of 0.3 N hydrochloric acid required to reduce the pHto 4 was 20.5 mils. A second liquid alkaline builder was preparedcontaining 20% by weight sodium hydroxide, 2% by weight borax, and 78%by weight water. The pH of a 0.2% aqueous solution of this builder was 1L9. The solution required 17.3 milliliters of 0.3 N hydrochloric acid toobtain the pH 4 level. A third liquid alkaline builder was preparedcontaining 20% by weight sodium hydroxide, 2% borax, 1% of ananti-redeposition agent which was the sodium salt ofcarboxymethylcellulose, the remainder of the builder being water. Theinitial pH of a 0.2% aqueous solution of this builder was 1 1.8. Thissolution required 16.1 milliliters of the same hydrochloric acid toreach the same pH point of 4. It will thus be seen that the addition ofborax reduced the alkalinity of the liquid builder solution to a markedamount inasmuch as less acid was required to achieve the same pH. Thealkaline builder solution containing the anti-redeposition agentrequired only 16.] milliliters to reach the pH of 4. It is believed thatthe slight further reduction in alkalinity in that solution over thecaustic/borax solution was due to the physical entrapment of thehydroxyl ions by the anti-redeposition agent rather than furtherchemical reduction of the hydroxyl ion concentration.

EXAMPLE ll The detergency effectiveness of the alkaline builder of thisinvention was determined by washing crankcase oil soiled swatches ofpolyester-cotton cloths in an aqueous solution of the liquid laundrydetergent system containing the alkaline builder to be evaluated underthe following conditions:

1. water temperature I80 F.,

2. detergent concentration 0.25% by weight commercial nonionic liquiddetergent mixture, 0.5% liquid alkaline builder as specified,

3. time 20 minutes.

The liquid nonionic commercial detergent used in the examples containeda nonionic liquid detergent polyethylene glycol ether of linear alcoholhaving a HLB value of l3.3 (45% of the total), a nonionic modifiedalkylene oxide condensation of a linear alcohol having a HLB value ofI50 (constituting [5% of the total composition), optical brightener,0.1% of the total composition, aliphatic solvent, comprising 34.9% ofthe total composition and the remaining 5% was water.

The swatches were washed in an apparatus often referred to as theLaunder-Ometer" which is the offieial method of American Association ofTextile Chemists and Colorists which may be found in the associationsMonograph No. 3, First Edition, published I949, Second Edition publishedI968. The apparatus consists essentially of a thermostaticallycontrolled waterbath in which is mounted a rotary rack or frame soconstructed that 20 l-pint Mason jars may be clamped to it in rows offive opposite to each other. A sample of cloth soiled with a standardartificial soil is placed in each jar along with a measured volume ofdetergent solution and a number of small rubber or stainless steelballs. The total volume of water, detergent and builder is 100milliliters. As the jar holder rotates, each jar describes a completecircle causing the balls in the solution to tumble about. This suppliesthe mechanical action needed for good detergency.

After washing, rinsing and drying the amounts of soil removal, that is,the amount of cleaning performed on each swatch was determined by use ofthe Reflectometer, manufactured by Hunter Associates Laboratory, usingthe Hunterlab D-40 green Reflectometer readings as the final result.Three swatches were washed and individually read to determine an averagevalue. It should be noted that the detergent solution used in washing nothickener or anti-redeposition agent was used in the formulation.

In this test the liquid alkaline builder was a solution containing 20%by weight sodium hydroxide and 80% by weight water. Five different usedcrankcase oils were used to soil the various swatches by placing onedrop of oil from each near the edge of a polyester-cotton 65/35 blendswatch in a pentagonal form leaving the center of the swatch unsoiled.The swatches were 4% inches X 4% inches in size. The Reflectometerreadings (an average of 3 tests) for oil No. 1 was 43.9; the reading foroil No. 2 was 42.3; No. 3 oil was 40.2; No. 4 oil was 38.6; and No. 5oil was 12.8 for a summation of the readings value of 177.8.

EXAMPLES lll-Vl Following the procedure of Example 11 except fordifference in the liquid alkaline builder solution employed, Examples111 through V! were performed and the test data is noted underneath eachexample heading. Throughout all tests the same identification wasmaintained for each lot of used crankcase oil.

EXAMPLE Ill The liquid alkaline builder used in this example contained20% sodium hydroxide, 1% borax (that is, 5% by weight of the sodiumhydroxide initially employed) and 79% water. The resulting sodiummetaborate content of the solution was 6.5% of the sodium hydroxideused. The Reflectometer readings for the oils were as follows: Oil No. l44.2; oil No. 2 44.3; oil No. 3 42.6; oil No. 4 41.5; and oil No. 5 13.1for a sum of reflectance readings value of 185.7

EXAMPLE IV The liquid alkaline builder of this example contained 20% byweight sodium hydroxide, 1.3% borax (that is, 635% by weight based onthe amount of initially present sodium hydroxide), and 78.7% water. Theresulting sodium metaborate content of the solution was 1.7% of thetotal solution. The Reflectometer readings were: Oil N0. 1 45.8; oil No.2 43.5; oil No. 3 43.0; oil No. 4 40.7; and oil No. 5 12.0 for a sum ofreflectance readings value of 185.0.

EXAMPLE V In this example the liquid alkaline builder solution contained20% sodium hydroxide, 2% borax (that is, by weight when based on sodiumhydroxide initially present), and 78% water. The resulting sodiummetaborate content of the solution was 13.0% of the sodium hydroxideused. The Reflectometer readings were as follows: Oil No. 1 46.2; oilNo. 2 45.2; oil

6 No.3 44.5; oil No. 4 41.5; and oil No. 5 17.2 for a sum of reflectancereadings value of 194.6.

Similar results will be obtained when potassium hydroxide is substitutedfor the sodium hydroxide above.

EXAMPLE V] In this example the liquid alkaline builder solutioncontained 20% by weight sodium hydroxide, 4% borax (that is, 20% byweight when based on sodium hydroxide used), and 76% water. Theresulting sodium metaborate content of the solution is 5.2% of the totalsolution or 26% of the sodium hydroxide used. The Reflectometer readingswere as follows: Oil No. l 44.1; oil No.2 38.3; oil No. 3 40.4; oil No.4 40.3; and oil No. 5 13.5 for a summation of reflectance readings valueof 176.6.

It will be seen in comparing the sum of reflectance values, which is themore indicative figure of the Reflectometer values obtained, in Examplesll through V1 that the detergency value or effect of no borax and 4%borax in the builder of Example V1 is substantially the same and thatunder these conditions the borax has no effect. However, Examples 111and [V point out increasing the amount of borax 1% and 1.3%,respectively, has a material effect on the cleaning ability of thesolution. The highest cleaning effect is obtained in Example V wherein2% borax was added to the alkaline builder, that is, the ratio of sodiumhydroxide to borax was 10 to 1. The reflectance value was 194.6, a 10%increase in cleaning over the similar situation where no borax, or twiceas much borax, was employed. In view of the prior art, it was surprisingto find such a material difference concentrated in such a short range ofborax addition values. In scanning the individual oil values, it will benoted that the 2% borax addition of Example V in each instance issubstantially above the values for no borax or for 4% borax.

EXAMPLE Vll To indicate the seriousness of the breakdown of polyesterson exposure to caustic in solution, the following test was prepared.Polyester film samples, cut to 3 inches x 1% inches dimensions (0.003inch thickness) were prepared for use by boiling for one-half hour in a3% hydrochloric acid solution. The scoured samples were than placed inweighing bottles, dried for one hour at 1 l0-120 C. and then weighed.The pretreated and weighed polyester samples were added to 500 milliterswide mounted, conical flask containing 250 grams of alkali solutionindicated below. The units were equipped to maintain reflux conditionsand the film samples were processed for a period of 2.382 hours at C.After treatment the film samples were again scoured with 3% hydrochloricacid solutions, dried, cooled and weighed to a constant weight. Thedifference between the original weight and the final weight is statedbelow as a percent of theoriginal weight. Solution 1 had a molarity of0.1234 and the polyester film had a weight loss of 0.67%. The secondsolution had a molarity of 0.4089 for a weight loss of 3.81%. The thirdsolution had a molarity of 0.8360 for a weight loss of 13.5%. The fourthsolution had a molarity of 1.8140 for a weight loss of 23.12%. Thus, itcan be concluded that the progressive effect of strong alkali solutionsis to degrade the polyester in the wash-andwear fabric over a period oftime.

For solutions 5 and 6 the time was changed to 2.012 hours and themolarity was 2.1727, the temperature being varied. Solution at atemperature of 60 C. had a polyester weight loss of l.4l% and solution 6at 90 C. had a polyester weight loss of l.4l% and solution 6 at 90 C.had a polyester weight loss of [4.7%.

For solutions 7 and 8 the temperature was l00 C., the molarity was1.3160 and the time was varied. With solution 7 the time of exposure was4 hours and the polyester weight loss was 33.75%. With solution 8 thetime of exposure was 6 hours and the polyester weight loss was 50.56%.

Therefore, the rate of weight loss of the polyester in the wash-and-wearfabric is also temperature depen dent as well as dependent upon themolarity of the alkaline builder. The greater the exposure time to thecaustic, i.e., the greater the number of washings of the garment orfabric, and the higher the temperature used, which is often the case inwhite goods or flat goods, the quicker the fabric will be disrupted bythe caustic alkaline builder. Therefore, the invention confers a realand valuable result by decreasing the hydroxyl exposure time (thecaustic quality of the alkaline builder) while at the same timeincreasing the amount of cleaning ability.

The foregoing examples have been described in the above specificationfor the purpose of illustration and not limitation. Many othermodifications and ramifications based on this disclosure will naturallysuggest themselves to those skilled in the art. These are intended to becomprehended as within the scope of this invention.

The embodiment of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a method of cleaning fabrics with an aqueous solution containingalkali metal hydroxide builder selected from the group consisting ofsodium hydroxide and potassium hydroxide, the improvement wherein boraxis included in said aqueous solution in an amount from about 5 to 15weight percent of the amount of said hydroxide present. thereby formingin situ alkali metal mataborate in an amount from about 6.5 to 19.5weight percent of the amount of said hydroxide initially present.

2. The improvement of claim I wherein said alkali metal hydroxide issodium hydroxide.

3. The improvement of claim 1 wherein the amount of said borate presentis about 13 percent by weight of the amount of said alkali metalhydroxide.

4. The improvement of claim 1 wherein the amount of said borax is fromabout 8 to 12 percent by weight of the amount of said alkali metalhydroxide.

S. An aqueous alkaline builder solution consisting essentially of 10 to30 percent by weight alkali metal hydroxide selected from the groupconsisting of sodium hydroxide and potassium hydroxide, borax in anamount from about 5 to 15 weight percent of said hy droxide and formingin situ alkali metal metaborate in an amount from about 6.5 to I weightpercent of the amount of said hydroxide initially present, and fromabout 0.25 to about l.5 weight percent of antiredep0- sition agent,balance water.

6. The solution of claim 5 wherein said alkali metal hydroxide is sodiumhydroxide.

7. The solution of claim 5 wherein said anti-redeposition agent isselected from the group consisting of the alkali and ammonium salts ofcarboxymethylcellulose, polyvinyl alcohol, polyvinyl pyrrolidone andhydroxyethyl cellulose.

8. The solution of claim 7 wherein the amount of said borax is fromabout 8 to 12 percent by weight of said hydroxide.

9. The solution of claim 6 wherein the amount of said anti-redepositionagent is from about 0.75 to 1 percent. i lk

1. IN A METHOD OF CLEANING FABRICS WITH AN AQUEOUS SOLUTION CONTAINING ALKALI METAL HYDROXIDE BUILDER SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE AND POTASSIUM HYDROXIDE, THE IMPROVEMENT WHEREIN BORAX IS INCLUDED IN SAID AQUEOUS SOLUTION IN AN AMOUNT FROM ABOUT 5 TO 15 WEIGHT PERCENT OF THE AMOUNT OF SAID HYDROXIDE PRESENT, THEREBY FORMING IN SITU ALKALI METAL MATABORATE IN AN AMOUNT FROM ABOUT 6.5 TO 19.5 WEIGHT PERCENT OF THE AMOUNT OF SAID HYDROXIDE INITIALLY PRESENT.
 2. The improvement of claim 1 wherein said alkali metal hydroxide is sodium hydroxide.
 3. The improvement of claim 1 wherein the amount of said borate present is about 13 percent by weight of the amount of said alkali metal hydroxide.
 4. The improvement of claim 1 wherein the amount of said borax is from about 8 to 12 percent by weight of the amount of said alkali metal hydroxide.
 5. An aqueous alkaline builder solution consisting essentially of 10 to 30 percent by weight alkali metal hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide, borax in an amount from about 5 to 15 weight percent of said hydroxide and forming in situ alkali metal metaborate in an amount from about 6.5 to 19.5 weight percent of the amount of said hydroxide initially present, and from about 0.25 to about 1.5 weight percent of anti-redeposition agent, balance water.
 6. The solution of claim 5 wherein said alkali metal hydroxide is sodium hydroxide.
 7. The solution of claim 5 wherein said anti-redeposition agent is selected from the group consisting of the alkali and ammonium salts of carboxymethylcellulose, polyvinyl alcohol, polyvinyl pyrrolidone and hydroxyethyl cellulose.
 8. The solution of claim 7 wherein the amount of said borax is from about 8 to 12 percent by weight of said hydroxide.
 9. The solution of claim 6 wherein the amount of said anti-redeposition agent is from about 0.75 to 1 percent. 